Socks provide comfort, insulation and protection to the feet of the wearer. Socks are produced in a variety of styles to serve numerous functions, including dress, casual, and athletic, with additional variations achieved through use of different yarns and patterns.
Athletic socks are used in many activities, such as in walking, tennis, basketball, and skiing, all of which can cause the feet to perspire and be fatigued or injured. It has long been recognized that by increasing the thickness of the sock, perspiration is more effectively absorbed and any impact from the athletic activity is cushioned.
Socks are almost universally made by knitting on what is known in the trade as a circular knitting machine. A circular knitting machine knits a tubular fabric structure through the controlled actions of a multiplicity of latch needles and sinkers on a length of yarn. A typical circular knitting machine in use today is a Lonati 454 J machine, made by the Lonati Company, S.P.A. of Brescia, Italy. The Lonati 454 J machine has 108 latch needles that are located circumferentially around its needle cylinder. The knitting action as well as the stitch density is controlled through a program of instructions installed on a microprocessor. This type of machine also incorporates a dial plate with hooks as later referred to.
Single, as well as double layer socks are generally knit with a rim surrounding an opening at the leg portion and an opening at the toe portion. The toe opening of a machine knit sock is typically closed in a separate operation performed on a model 222 Complett automatic sewing machine made by Conti Complett, S.P.A. of Milan, Italy. The Complett sewing machine has a guide with a slot through which its operator passes a relatively thin fabric segment adjacent the toe opening of the sock. The sewing machine has a pair of opposed gripper chains that move the sock through a trimming section to remove the fabric that is beyond the relatively thin segment and then through a sewing section to close the sock toe seam.
Traditional means of increasing the thickness of socks involves producing a pair of socks with a terry layer such as that disclosed in U.S. Pat. No. 3,796,067 to East in which the sock has a smooth knit layer and a terry layer. The '067 patent teaches forming the sock by knitting of an elongate tube and inverting one half within the other half to achieve two layers.
Socks made with partial multiple layers are disclosed in U.S. Pat. No. 4,431,096 to Safrit et al. which shows a sock having a triple layer fabric in the foot portion; and U.S. Pat. No. 4,467,626 to Coble et al. which shows a sock with a double layer in the foot portion. Socks made with a full multiple layer are also disclosed in U.S. Pat. No. 4,571,290 to Hursh et al. which shows a two-ply athletic sock with low-friction interface surfaces; and U.S. Pat. Nos. 5,675,992 and 5,778,702 to Wrightenberry which show double layer socks and methods of making such socks.
Double layer socks of the kind described above provide the desired multiple layers, but have the disadvantage of requiring a relatively large labor component to produce, resulting in higher prices to the consumer or lower profit for the manufacturer. Many of these double layer socks are closed at the toe by sewing the toe of the inner layer closed and then sewing the toe of the outer layer closed, in which case the inner and outer toe sections are not connected, leading to bunching, twisting and other causes of discomfort to the wearer. Alternatively, the inner and outer toes are closed together by manually aligning the knitting wales of the two layers to avoid the undesired twisting, but increase the time and cost to manufacture.
A further method of construction of a double layer sock is disclosed in U.S. Pat. No. 4,958,507 to Allaire et al. The method of the '507 patent begins with the step of knitting a sock with a first course that is transferred to a transfer plate (also known as a dial plate) to remain in standby while the balance of the double layer sock body is knitted. The retained first course is then transferred from the dial plate at the end of the knitting process to form a connection between the inner layer and the outer layer at the toe. When the inner and outer layers are connected at the toe, additional courses are knit to form a single tubular terminal layer that extends beyond the two sock layers. The method of the '507 patent overcomes the alignment and twisting problem noted above, but fails to provide what is later referred to as a low stitch-density "guide" fabric which enables the toe seam to be efficiently closed.
The object of the invention is thus to provide an improved method for producing a double layer sock and an improved sock produced by such method. Other objects will become apparent as the description proceeds.